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What is DSRC for the connected car?

Dedicated short-range communications technology, or DSRC, is one of the primary areas of research and development for a network exclusively for transportation-related uses. Here are some of the basics on DSRC.

What is DSRC?

DSRC is is “a two-way short-to-medium-range wireless communications capability that permits very high data transmission critical in communications-based active safety applications,” according to the U.S. Department of Transportation’s Intelligent Transportation Systems Joint Program Office, which heads up much of the research related to DSRC. The Federal Communications Communications Commission set aside 75 MHz of spectrum around the 5.9 GHz band (5.850-5.925 GHz) band in 1999 to be used for vehicle-related safety and mobility systems.

In general, intelligent transportation systems — smarter infrastructure, as well as vehicles with new driver assistance and eventually, autonomous driving features — are seen as a way to reduce traffic accidents and fatalities, as well as improve traffic congestion and fuel efficiency.

How will DSRC be used?

It is anticipated that DSRC will be used for both vehicle-to-vehicle communications as well as vehicle-to-infrastructure communications. The spectrum is seen as particularly useful for V2x communications because it can support very low-latency, secure transmissions; fast network acquisition and in general, the ability to handle rapid and frequent handovers that are inherent in a vehicle environment; as well as being highly robust in adverse weather conditions. ITS also notes that it is tolerant of multi-path transmission.

The DOT has identified more than 40 use cases for V2I technologies, such as the ability to pay for parking and tolls wirelessly, identify when a car is approach a curve too quickly and alert the driver; adjusting traffic signals to accommodate first responders in an emergency; and alert drivers of conditions such as road construction, among others.

According to the National Connected Vehicle Field Infrastructure Footprint Analysis report (pdf here) conducted by the American Association of State Highway and Transportation Officials, a connected vehicle infrastructure deployment is expected to leverage technologies that include cellular and Wi-Fi as well as DSRC and would typically include:

• Roadside communications equipment and enclosures, mountings, power, and network backhaul.

• Traffic signal controller interfaces for applications that require signal phase and timing data.

• Systems and processes required to support management of security credentials and ensure a trusted network.

• Mapping services that provide highly detailed roadway geometries, signage, and asset locations for the various connected vehicle applications.

• Positioning services for resolving vehicle locations to high accuracy and precision.

• Data servers for collecting and processing data provided by vehicles and for distributing information, advisories, and alerts to users.

What is the status of DSRC?

According to a report published last week on the connected car by the Government Accountability Office, the US DOT “plans to provide up to $100 million through its Connected Vehicle pilot program for projects that will deploy V2I technologies in real-world settings” over the next five years.

However, the GAO report also pointed out that “the full extent of V2I technologies’ benefits and costs is unclear because test deployments have been limited thus far; however, DOT has supported initial research into the potential benefits and costs.”

What are some of the challenges for DSRC and the connected car?

The GAO identified the following challenges, specifically for V2I communications:

(1) making sure that possible spectrum-sharing in the DSRC band will not adversely affect V2I performance

(2) addressing the lack of resources at the state and local level to deploy and maintain V2I technologies

(3) developing technical standards for interoperability

(4) developing and managing data security and addressing public perceptions related to privacy

(5) ensuring that drivers respond appropriately to V2I warnings

(6) addressing the uncertainties related to potential liability issues posed by V2I.

“DOT is collaborating with the automotive industry and state transportation officials, among others, to identify potential solutions to these challenges,” the GAO noted.


What are some current issues in regard to DSRC?

Although DSRC spectrum was set aside to be used for vehicle- and transportation-related systems, the federal government is trying to open up more spectrum to the wireless ecosystem in general — and DSRC isn’t immune to consideration. One particular area of concern is whether the 5.9 GHz spectrum would be opened up for spectrum sharing with Wi-Fi. Qualcomm made a proposal that involved divvying up the spectrum so that certain functions operated in different regions of the band, instead of sharing the entire allocation with some version of Wi-Fi’s listen-before-talk approach.

Automakers responded by protesting Qualcomm’s plan, although so far there has been more support for a spectrum-sharing approach offered by Cisco for V2V communications, which GM reportedly plans to begin implementing into its 2017 Cadillac CTS sedans.

The DOT released a device test plan in August (pdf here) designed to “characterize the existing radio frequency signal environment and identify the impacts to DSRC operations of unlicensed devices operating in the 5850-5925 MHz band and adjacent bands.”

The DOT also has accelerated its support of fore regulatory requirements for V2V capabilities in all new vehicles. In May, U.S. Transportation Secretary Anthony Foxx announced that after putting out a proposed rule-making in 2014 and planning to send a proposed rule to the Office of Management and Budget for review next year, the DOT is pushing its timeline forward and will send its proposal for OMB review by the end of 2015.


Looking to learn more on connected car technologies and challenges? Join RCR for its upcoming webinar on the topic, to be held Oct. 28th. An in-depth special report on the connected car will be published the same day. 

Image: Copyright: 06photo / 123RF Stock Photo

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